Prevalence of work related musculoskeletal disorders in active union carpenters.

OBJECTIVES: To determine the prevalence and risk factors for work related musculoskeletal disorders among union carpenters. METHODS: A detailed questionnaire on musculoskeletal symptoms and work history was administered to 522 carpenters. The symptom questions assessed if carpenters experienced pain, numbness, or tingling in a particular body region. A subset of this group then received a physical examination of the upper extremities and knees. RESULTS: The study group was primarily white (94.9%) and male (97.8%) with a mean age of 42.3 years. The highest prevalence of work related musculoskeletal disorders cases by carpentry specialty ranged from 20%-24% for those doing drywall or ceiling, finishing or framing, and the building of concrete forms. Generally, as duration of employment increased, the prevalence of symptoms increased. An adjusted logistic regression analysis showed that the group with the longest (> or = 20 years) duration of employment in carpentry was significantly associated with work related musculoskeletal disorders of the shoulders (odds ratio (OR) 3.2, 95% confidence interval (95% CI) 1.1 to 8.9), hands or wrists (OR 3.1, 95% CI 1.1 to 8.4), and knees (OR 3.5, 95% CI 1.3 to 9.2). Also, analyses showed that carpenters who reported that they had little or no influence over their work schedule had significant increases of work related musculoskeletal disorders of the shoulders, hips, and knees with ORs of 1.9 (95% CI 1.1 to 3.2), 2.9 (95% CI 1.1 to 7.2), and 2.3 (95% CI 1.2 to 4.1), respectively. Feeling exhausted at the end of day was also a significant risk factor for work related musculoskeletal disorders of the knee (OR 1.8, 95% CI 1.1 to 3.1). Upper extremity disorders were the most prevalent work related musculoskeletal disorders reported among all carpenters. Drywall or ceiling activities involve a considerable amount of repetitive motion and awkward postures often with arms raised holding heavy dry walls in place, whereas form work is notable for extensive lumbar flexion and had the two highest rates of work related musculoskeletal disorders. The psychosocial element of job control was associated with both upper and lower extremity disorders. These union carpenters, who were relatively young, already were experiencing considerable work related physical problems. CONCLUSION: This study supports the need for vigilant ergonomic intervention at job sites and early ergonomic education as an integral part of apprenticeship school training to ensure that carpenters remain fit and healthy throughout their working lifetime.

Reliability of questionnaire information measuring musculoskeletal symptoms and work histories.

This study was designed to assess the test-retest reliability of a musculoskeletal symptom and work history (MSWH) questionnaire administered to 522 carpenters A 10% subgroup of carpenters completing the original interview was selected for the retest interview. The areas addressed included recall of work-related musculoskeletal symptoms, prior medical conditions, prior injuries, recall of work histories, and psychosocial items. The results show that for these sections of the MSWH questionnaire the observed agreements ranged from 75.5 to 97.0%, and the calculated kappa estimates ranged from 0.46 to 0.77. Injury to body regions, job specialty, and prior medical history had the highest kappa values of K = .70 or greater. Reliability of reporting frequency of job duties such as flooring and finishing was excellent, with kappa = 0.73 (95% confidence interval = 0.66, 0.80). Based on these results, the overall reliability of the MSWH questionnaire is very good.

Alterations of histone phosphorylation in rat spleen cells after treatment with the aromatic amine, 4,4'-methylene-bis(2-chloroaniline).

Alterations of the phosphorylation pattern of histones by the carcinogen, 4,4'-methylene-bis(2-chloroaniline) (MOCA) were investigated using rodent spleen cells. Spleen cells were isolated from Sprague-Dawley rats and treated with either 5, 10, 25, or 50 microM MOCA or acetone vehicle controls for 1, 2, 4, or 8 hours. Cells were incubated with 32P-phosphoric acid, and histones from these cells were fractionated utilizing two-dimensional polyacrylamide gel electrophoresis. Marked stimulation of histone phosphorylation was observed with the 10 microM MOCA treatment. A transient decrease in histone phosphorylation was observed at the 1 and 2 hour time points followed by a marked stimulation at 4 hours.

ortho-toluidine blood protein adducts: HPLC analysis with fluorescence detection after a single dose in the adult male rat.

Hemoglobin (Hb) and albumin (Alb) adducts of the suspect human carcinogen ortho-toluidine (OT) were quantified in blood samples collected from rats after a single i.p. injection. Mild alkaline hydrolysis of Hb adducted with [14C]OT followed by extraction with ethyl acetate resulted in recovery of 63% of the bound radioactivity. HPLC analysis revealed a single radiolabeled peak which was identified as OT by GC-MS. In subsequent experiments Hb and Alb adduct levels were determined by HPLC analysis of this cleavage product using fluorescence detection. 4-Ethylaniline was used as internal standard. The detection limit for OT was approximately 450 pg/injection or 5 pmol/mg Hb. Mean adduct levels for Hb increased rapidly over the first 4 hr with the highest (ng/mg Hb +/- SD) 3.7 +/- 0.5 detected 24 hr after OT administration at 50 mg/kg body wt. In contrast, adduct levels for pooled Alb samples increased from 0.7 ng/mg Alb at 2 hr to 2.5 ng/mg Alb at 4 hr, but were not detectable 24 hr after dosing. Hb adducts showed a linear relationship for OT doses of 10, 20, 40, 50, and 100 mg/kg body wt. The Hb adduct t1/2 (11 days) was determined after a single 100 mg/kg OT dose. Hb adduct levels were quantifiable (1.3 +/- 0.2 ng/mg Hb) by HPLC/fluorescence 28 days after 100 mg/kg OT. Although Hb and Alb adducts differ in stability, a ratio of such OT adducts may be useful in long-term industrial biomonitoring for evaluation of OT exposure.

Binding characteristics of ortho-toluidine to rat hemoglobin and albumin.

The binding characteristics of [14C]ortho-toluidine (OT), a suspect human carcinogen, were investigated in male Sprague-Dawley rats. Rats were administered [14C]OT i.p. at 10, 20, 40, 50, or 100 mg/kg body weight, then sacrificed at 2, 4, 8, 18, 24, 48, or 72 h, or 7, 14, or 28 days. Hemoglobin (Hb) and albumin (Alb) were isolated from blood, and OT binding was determined by liquid scintillation counting. For Alb, peak binding occurred at 50 mg/kg at the 4-h time point (15.6 ng OT/mg Alb), while for Hb peak binding was observed at 24 h at the 100 mg/kg dose (23.0 +/- 5.1 ng OT/mg Hb). OT-Alb binding was not linear; however, OT-Hb binding appeared to increase linearly in a dose-dependent manner. Biological half-lives of OT bound to Alb or Hb were observed to be 2.6 and 12.3 days, respectively, after rats were administered a single dose of [14C]OT and sacrificed after 4 h to 28 days. The effect of route of administration on OT-Hb adduct formation was investigated, and approximately a two-fold increase in radioactivity bound to Hb was observed after i.p. administration of 100 mg/kg [14C]OT versus oral intubation. Additional studies were carried out to investigate the effect of microsomal enzyme induction. An increase in OT-Hb binding was seen in rats pretreated with phenobarbital compared to rats pretreated with beta-naphthoflavone or without pretreatment; however, this increase was not statistically significant. These results suggest that OT-Hb and OT-Alb adduct formation may be a valuable biomarker for assessing workplace exposure.